src: add masquerade support

index e04ab7d..a182f74 100644
@@ -70,6 +70,12 @@ struct nat_stmt {
 
 extern struct stmt *nat_stmt_alloc(const struct location *loc);
 
+struct masq_stmt {
+	uint32_t		flags;
+};
+
+extern struct stmt *masq_stmt_alloc(const struct location *loc);
+
 struct queue_stmt {
 	struct expr		*queue;
 	uint16_t		flags;

@@ -100,6 +106,7 @@ extern struct stmt *ct_stmt_alloc(const struct location *loc,
  * @STMT_LOG:		log statement
  * @STMT_REJECT:	REJECT statement
  * @STMT_NAT:		NAT statement
+ * @STMT_MASQ:		masquerade statement
  * @STMT_QUEUE:		QUEUE statement
  * @STMT_CT:		conntrack statement
  */

@@ -113,6 +120,7 @@ enum stmt_types {
 	STMT_LOG,
 	STMT_REJECT,
 	STMT_NAT,
+	STMT_MASQ,
 	STMT_QUEUE,
 	STMT_CT,
 };

@@ -160,6 +168,7 @@ struct stmt {
 		struct limit_stmt	limit;
 		struct reject_stmt	reject;
 		struct nat_stmt		nat;
+		struct masq_stmt	masq;
 		struct queue_stmt	queue;
 		struct ct_stmt		ct;
 	};

index 284ee72..ac35bf6 100644
@@ -1171,6 +1171,32 @@ static int stmt_evaluate_nat(struct eval_ctx *ctx, struct stmt *stmt)
 	return 0;
 }
 
+static int stmt_evaluate_masq(struct eval_ctx *ctx, struct stmt *stmt)
+{
+	struct proto_ctx *pctx = &ctx->pctx;
+
+	if (!pctx)
+		goto out;
+
+	switch (pctx->family) {
+	case AF_INET:
+		expr_set_context(&ctx->ectx, &ipaddr_type,
+				4 * BITS_PER_BYTE);
+		break;
+	case AF_INET6:
+		expr_set_context(&ctx->ectx, &ip6addr_type,
+				 16 * BITS_PER_BYTE);
+		break;
+	default:
+		return stmt_error(ctx, stmt,
+				  "masquerade family must be ip or ipv6");
+	}
+
+out:
+	stmt->flags |= STMT_F_TERMINAL;
+	return 0;
+}
+
 static int stmt_evaluate_ct(struct eval_ctx *ctx, struct stmt *stmt)
 {
 	expr_set_context(&ctx->ectx, stmt->ct.tmpl->dtype,

@@ -1231,6 +1257,8 @@ static int stmt_evaluate(struct eval_ctx *ctx, struct stmt *stmt)
 		return stmt_evaluate_reject(ctx, stmt);
 	case STMT_NAT:
 		return stmt_evaluate_nat(ctx, stmt);
+	case STMT_MASQ:
+		return stmt_evaluate_masq(ctx, stmt);
 	case STMT_QUEUE:
 		return stmt_evaluate_queue(ctx, stmt);
 	case STMT_CT:

index e2a13d3..7785ce4 100644
@@ -558,6 +558,21 @@ static void netlink_parse_nat(struct netlink_parse_ctx *ctx,
 	list_add_tail(&stmt->list, &ctx->rule->stmts);
 }
 
+static void netlink_parse_masq(struct netlink_parse_ctx *ctx,
+			       const struct location *loc,
+			       const struct nft_rule_expr *nle)
+{
+	struct stmt *stmt;
+
+	stmt = masq_stmt_alloc(loc);
+
+	if (nft_rule_expr_is_set(nle, NFT_EXPR_MASQ_FLAGS))
+		stmt->masq.flags = nft_rule_expr_get_u32(nle,
+							 NFT_EXPR_MASQ_FLAGS);
+
+	list_add_tail(&stmt->list, &ctx->rule->stmts);
+}
+
 static void netlink_parse_queue(struct netlink_parse_ctx *ctx,
 			      const struct location *loc,
 			      const struct nft_rule_expr *nle)

@@ -604,6 +619,7 @@ static const struct {
 	{ .name = "limit",	.parse = netlink_parse_limit },
 	{ .name = "reject",	.parse = netlink_parse_reject },
 	{ .name = "nat",	.parse = netlink_parse_nat },
+	{ .name = "masq",	.parse = netlink_parse_masq },
 	{ .name = "queue",	.parse = netlink_parse_queue },
 };
 

index 36b56ff..c5aa0b4 100644
@@ -685,6 +685,19 @@ static void netlink_gen_nat_stmt(struct netlink_linearize_ctx *ctx,
 	nft_rule_add_expr(ctx->nlr, nle);
 }
 
+static void netlink_gen_masq_stmt(struct netlink_linearize_ctx *ctx,
+				  const struct stmt *stmt)
+{
+	struct nft_rule_expr *nle;
+
+	nle = alloc_nft_expr("masq");
+	if (stmt->masq.flags != 0)
+		nft_rule_expr_set_u32(nle, NFT_EXPR_MASQ_FLAGS,
+				      stmt->masq.flags);
+
+	nft_rule_add_expr(ctx->nlr, nle);
+}
+
 static void netlink_gen_queue_stmt(struct netlink_linearize_ctx *ctx,
 				 const struct stmt *stmt)
 {

@@ -749,6 +762,8 @@ static void netlink_gen_stmt(struct netlink_linearize_ctx *ctx,
 		return netlink_gen_reject_stmt(ctx, stmt);
 	case STMT_NAT:
 		return netlink_gen_nat_stmt(ctx, stmt);
+	case STMT_MASQ:
+		return netlink_gen_masq_stmt(ctx, stmt);
 	case STMT_QUEUE:
 		return netlink_gen_queue_stmt(ctx, stmt);
 	case STMT_CT:

index 1b2c31c..3fa6d66 100644
@@ -299,3 +299,21 @@ struct stmt *nat_stmt_alloc(const struct location *loc)
 {
 	return stmt_alloc(loc, &nat_stmt_ops);
 }
+
+static void masq_stmt_print(const struct stmt *stmt)
+{
+	printf("masquerade");
+
+	print_nf_nat_flags(stmt->masq.flags);
+}
+
+static const struct stmt_ops masq_stmt_ops = {
+	.type		= STMT_MASQ,
+	.name		= "masq",
+	.print		= masq_stmt_print,
+};
+
+struct stmt *masq_stmt_alloc(const struct location *loc)
+{
+	return stmt_alloc(loc, &masq_stmt_ops);
+}